Effect of Ranibizumab Versus Bevacizumab on the Macular Perfusion in Diabetic Macular Edema

The Early Treatment Diabetic Retinopathy Study (ETDRS) group founded guidelines for treating patients with clinically significant diabetic macular edema (DME) with focal/grid macular laser photocoagulation. Since then, macular laser, and steroids, were the main therapies for the treatment of DME until anti-vascular endothelial growth factors (anti-VEGF) drugs were developed after a growing body of scientific evidence implicated VEGF in the pathophysiologic process of DME. Anti-VEGF drugs have been implicated in the treatment of DME. VEGF has been shown to play an important role in the occurrence of increased vascular permeability in DME. VEGF levels are significantly higher in patients with DME and extensive leakage than in patients with minimal leakage. Many studies such as Diabetic Retinopathy Clinical Research \[DRCR\] Network studies, RESTORE Study, RISE and RIDE Research Group, and The BOLT Study have supported the use of anti-VEGF agents in the treatment of DME with better visual outcomes using anti-VEGF injections alone or in combination with other treatments. Several ocular complications of intravitreal anti-VEGF injections have been reported including endophthalmitis, cataract, and retinal detachment. The different effects on macular perfusion between different anti-VEGFs have yet to be fully concluded with mixed conclusions that it increases or decreases or has no effect on perfusion of the macula in response to Anti-VEGF treatment. In many of these studies, however, patients with more ischemic retinas were not included. Retinal ischemia is a vital factor determining the diabetic retinopathy progression and prognosis. Optical coherence tomography angiography (OCTA) detects blood flow by analyzing signal decorrelation between two sequential OCT cross-sectional scans at the same location. As it detects the movements of red blood corpuscles within the vessels, compared to the stationary retinal surroundings, which will result in signal disparity and imaging The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm improves the signal to noise ratio. OCTA is considered a reliable tool in the detection and quantification of macular ischemia in diabetics. In this study, the investigators aim to compare the effect of repeated intravitreal injections of ranibizumab and bevacizumab on the perfusion of different capillary layers in the macula of diabetic patients using OCTA.